Activation Of TGR5 With INT-777 Attenuates Oxidative Stress And Neuronal Apoptosis Via CAMP/PKCε/ALDH2 Pathway After Subarachnoid Hemorrhage In Rats.

Background:Oxidative stress and neuronal apoptosis play important roles in the pathogenesis of early brain injury(EBI)after subarachnoid hemorrhage(SAH).The activation of TGR5,a novel membrane-bound bile acid receptor,possesses anti-oxidative stress and anti-apoptotic effects in hepatobiliary disease and kidney disease.The present study aimed to explore the neuroprotective effect of TGR5 activation against EBI after SAH and the potential underlying mechanisms.Methods:The endovascular perforation model of SAH was performed on 199 Sprague Dawley rats to investigate the beneficial effects of TGR5 activation after SAH.INT-777,a specific synthetic TGR5 agonist,was administered intranasally at 1 h after SAH induction.TGR5 CRISPR and ALDH2 CRISPR were administered intracerebroventricularly at 48 h before SAH to illuminate potential mechanisms.The SAH grade,short-term and long-term neurobehavioral tests,TUNEL staining,Fluoro-Jade C staining,Nissl staining,immunofluorescence staining,and western blots were performed at 24 h after SAH.Results:The expressions of endogenous TGR5 and ALDH2 gradually increased and peaked at 24 h after SAH.TGR5 was expressed primarily in neurons,as well as in astrocytes and microglia.The activation of TGR5 with INT-777 significantly improved the short-term and long-term neurological deficits,accompanied by reduced the oxidative stress and neuronal apoptosis at 24 h after SAH.Moreover,INT-777 treatment significantly increased the expressions of TGR5,cAMP,phosphorylated PKCε,ALDH2,HO-1,and Bcl-2,while downregulated the expressions of 4-HNE,Bax,and Cleaved Caspase-3.TGR5 CRISPR and ALDH2 CRISPR abolished the neuroprotective effects of TGR5 activation after SAHConclusions:In summary,the activation of TGR5 with INT-777 attenuated oxidative stress and neuronal apoptosis via the cAMP/PKCε/ALDH2 signaling pathway after SAH in rats.Furthermore,TGR5 may serve as a novel therapeutic target to ameliorate EBI after SAH.